<template>
    <div>
    <router-link
      tag="div"
      to="/"
      class="header-abs"
      v-show="showAbs">
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link>
    <div
      class="header-fixed"
      v-show="!showAbs"
      :style="opacityStyle"
    >
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name: "DetailHeader",
  data() {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    };
  },
  methods: {
    handleScroll() {
      const top = document.documentElement.scrollTop;
      if (top > 60) {
        let opacity = top / 140;
        opacity = opacity > 1 ? 1 : opacity;
        this.opacityStyle = { opacity };
        this.showAbs = false;
      } else {
        this.showAbs = true;
      }
    }
  },
  mounted() {
    window.addEventListener("scroll", this.handleScroll);
  },
  unmounted() {
    window.removeEventListener("scroll", this.handleScroll);
  }
};
</script>

<style scoped lang="stylus" rel="stylesheet/stylus">
@import '~styles/varibles.styl';

.header-abs {
    position: absolute;
    left: 0.2rem;
    top: 0.2rem;
    width: 0.8rem;
    height: 0.8rem;
    line-height: 0.8rem;
    border-radius: 0.4rem;
    text-align: center;
    background: rgba(0, 0, 0, 0.8);

    .header-abs-back {
        color: #fff;
        font-size: 0.4rem;
    }
}

.header-fixed {
    z-index: 2;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: $headerHeight;
    line-height: $headerHeight;
    text-align: center;
    color: #fff;
    background: $bgColor;
    font-size: 0.32rem;

    .header-fixed-back {
        position: absolute;
        top: 0;
        left: 0;
        width: 0.64rem;
        text-align: center;
        font-size: 0.4rem;
        color: #fff;
    }
}
</style>
